Process for producing infant formula products and acidic dairy products from milk

ABSTRACT

The invention pertains to a process for simultaneous producing an infant formula product and an acidic dairy product from defatted animal milk, comprising (a) processing the milk into a casein stream, a whey protein stream and a lactose stream, by: (i) subjecting the defatted animal milk to a filtration step over a microfiltration membrane capable of retaining bacteria and permeating milk proteins, to provide a debacterialized milk as permeate; (ii) subjecting the permeate originating from step (i) to a filtration step over a microfiltration membrane capable of retaining casein and permeating whey proteins, to provide a casein stream as retentate and a permeate comprising whey protein; (iii) fractionating the permeate originating from step (ii) into a whey protein stream and a lactose stream; (b) combining part of the casein stream, at least part of the whey protein stream originating from step (a) and a lactose source to obtain a recombined stream, wherein the lactose source comprises acid whey; (c) using the recombined stream originating from step (b) in the manufacture of the infant formula product; (d) using part of the casein stream originating from step (a) in the manufacture of the acidic dairy product. The invention further concerns the infant formula product obtainable by step (c) of the process according to the invention, and to the acidic dairy product obtainable by step (d) of the process according to the invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Phase of International PatentApplication No. PCT/EP2017/070123, filed Aug. 8, 2017, published on Feb.15, 2018 as WO/2018/029222 A1, which claims priority to InternationalPatent Application No. PCT/EP2016/068910, filed Aug. 8, 2016. Thecontents of these applications are herein incorporated by reference intheir entirety.

The invention is in the field of milk treatment, in particular thetreatment of defatted animal milk. The invention relates to theproduction of infant formula products, such as infant formula bases, aswell as acidic dairy products, from the same starting material. Theinvention further concerns the infant formula product and the acidicdairy product obtainable by the process according to the invention.

BACKGROUND

Human milk is considered the ‘golden standard’ for infant nutrition.Processing animal milk, for example cow's milk, to more resemble thecomposition of human milk is known in the art as ‘humanizing’ animalmilk. The process of humanizing animal milk involves changing the ratioof casein:whey proteins as found in animal milk (e.g. approximately80:20 for cow's milk) to the desired ratio for infant nutrition as foundin human milk, for example between 75:25 and 30:70, or usuallyapproximately 40:60, which is the ratio found in human milk in months0-6 post-partem. In addition, the mineral content of animal milk istypically higher than the content found in human milk. Thus humanizationof animal milk also involves reducing of the mineral content.

Preparation of products suitable for use in infant nutrition typicallyinvolves blending of various individually purified components in theappropriate ratios, either wet or dry. Current manufacturing processesrequire multiple dairy ingredients from intermediate suppliers,including skim milk or a concentrate thereof, including skim milkpowder, demineralised whey or a concentrate thereof, includingdemineralised whey powder, whey protein concentrates or isolates,normally as powders, and pure grade lactose, typically in powder form,to formulate a nutritionally balanced infant formula.

Membrane filtration processes for the manufacture of infant formulaproducts from milk are known from e.g. WO 2013/137714, WO 2015/041529,U.S. Pat. No. 5,503,865, EP 1133238, WO 2013/068653, WO 2014/163493 andWO 2014/163494. None disclose an efficient and cost-effective way toreduce waste streams, in particular the excess casein that typicallyremains when infant formula products are produced from milk. WO2015/041529 employs this excess casein to produce a nutritional productsuitable for feeding infants from 6-36 months of age.

There remains a need in the art for a process that enables efficient andcost-effective preparation of infant formula products from milk, whichfurther reduces the number of waste streams.

SUMMARY OF THE INVENTION

The invention pertains to a process for simultaneous producing an infantformula product and an acidic dairy product from defatted animal milk.The invention further concerns the infant formula product obtainable bythe process according to the invention, and to the dairy productobtainable by the process according to the invention. The processaccording to the invention comprises:

-   (a) processing the milk into a casein stream, a whey protein stream    and a lactose stream, by:    -   (i) subjecting the defatted animal milk to a filtration step        over a microfiltration membrane capable of retaining bacteria        and permeating milk proteins, to provide a debacterialized milk        as permeate;    -   (ii) subjecting the permeate originating from step (i) to a        filtration step over a microfiltration membrane capable of        retaining casein and permeating whey proteins, to provide a        casein stream as retentate and a permeate comprising whey        protein;    -   (iii) fractionating the permeate originating from step (ii) into        a whey protein stream and a lactose stream;-   (b) combining part of the casein stream, at least part of the whey    protein stream originating from step (a) and a lactose source to    obtain a recombined stream, wherein the lactose source comprises    acid whey;-   (c) using the recombined stream originating from step (b) in the    manufacture of the infant formula product;-   (d) using part of the casein stream originating from step (a) in the    manufacture of the acidic dairy product.

The process according to the invention elegantly makes use of allcomponents of the incoming defatted animal milk and minimizes the amountof waste streams that are obtained. According to a preferred embodiment,the process enables the formation of both an infant formula product andan acidic dairy product from the incoming defatted animal milk as singleprotein source. A further advantage of the process according to theinvention is that both products are efficiently and cost-effectivelyproduced, with minimal supplementation requirements.

LIST OF PREFERRED EMBODIMENTS

-   1. Process for producing an infant formula product and an acidic    dairy product from defatted animal milk, comprising:    -   (a) processing the milk into a casein stream, a whey protein        stream and a lactose stream, by:        -   (i) subjecting the defatted animal milk to a filtration step            over a microfiltration membrane capable of retaining            bacteria and permeating milk proteins, to provide a            debacterialized milk as permeate;        -   (ii) subjecting the permeate originating from step (i) to a            filtration step over a microfiltration membrane capable of            retaining casein and permeating whey proteins, to provide a            casein stream as retentate and a permeate comprising whey            protein;        -   (iii) fractionating the permeate originating from step (ii)            into a whey protein stream and a lactose stream;    -   (b) combining part of the casein stream, at least part of the        whey protein stream originating from step (a) and a lactose        source to obtain a recombined stream, wherein the lactose source        comprises acid whey;    -   (c) using the recombined stream originating from step (b) in the        manufacture of the infant formula product;    -   (d) using part of the casein stream originating from step (a) in        the manufacture of the acidic dairy product.-   2. Process according to embodiment 1, wherein the acid whey that is    used in the combining of step (b) is obtained as by-product during    the manufacture of step (d).-   3. Process according to embodiment 1 or 2, wherein the acid whey is    obtained as a liquid stream from a separation step during the    manufacture of an acidic dairy product.-   4. Process according to any one of the preceding embodiments,    wherein the acid whey is subjected to demineralization prior to    being used as lactose source in step (b), preferably wherein    demineralization comprises at least one of salt precipitation,    electrodialysis, lactose crystallization and ion exchange,    optionally in combination with nanofiltration.-   5. Process according to any one of the preceding embodiments,    wherein at least part of the lactose stream originating from    step (a) is used as lactose source in step (b) and/or is used in the    manufacture of step (d)-   6. Process according to embodiment 5, wherein part, preferably 50-95    wt % based on total weight of the lactose, of the lactose stream is    used as lactose source in step (b) and part of the lactose stream,    preferably the remaining part, is used in the manufacture step (d).-   7. Process according to any one of the preceding embodiments,    wherein the acid whey and at least part of the lactose stream    originating from step (a) are combined and subsequently subjected to    the demineralization according to embodiment 4 prior to being used    as lactose source in step (b).-   8. Process according to any one of the preceding embodiments,    wherein the combining of step (b) is done such that the whey protein    to casein weight ratio in the recombined stream is in the range of    90:10 to 40:60.-   9. Process according to any one of the preceding embodiments,    wherein step (d) involves combining the part of the casein stream    originating from step (a) with a whey protein source, preferably    with defatted animal milk, preferably wherein the weight ratio of    protein from the casein stream to protein from the whey protein    source is in the range of 0.1-9.0, most preferably in the range    0.5-2.0.-   10. Process according to any one of the preceding embodiments,    wherein 10-50 wt % of the casein stream originating from step (a),    based on total weight of the casein, is subjected to step (b) and    the remainder to step (d).-   11. Process according to any one of the preceding embodiments,    wherein the fraction of casein stream originating from step (a) that    is subjected to step (b) and that is used in step (d) is governed by    the desired whey protein to casein weight ratio in the recombined    stream.-   12. Process according to any one of the preceding embodiments,    wherein the volume concentration factor at which the ultrafiltration    step operates is in the range of 20-200.-   13. Process according to any one of the preceding embodiments,    wherein the manufacturing of step (c) includes at least one of    drying, concentrating, supplementing with vitamins, minerals, lipids    and/or dietary fibres and packaging.-   14. Process according to any one of the preceding embodiments,    wherein the acidic dairy product is selected from the group    consisting of fermented dairy products and acid cheeses, preferably    the acidic dairy product is a strained yogurt.-   15. Process according to any one of the preceding embodiments,    wherein defatted animal milk is the sole protein source for the    infant formula product, preferably for the both infant formula    product and the acidic dairy product.-   16. Infant formula product obtainable by step (c) of the process    according to any one of embodiments 1-15.-   17. Acidic dairy product obtainable by step (d) of the process    according to any one of embodiments 1-15.

DETAILED DESCRIPTION

In the process according to the invention defatted animal milk istreated to produce an infant formula product and an acidic dairyproduct. In the process, steps (a)-(c) concern the production of theinfant formula product and steps (a) and (d) the production of theacidic dairy product. The present invention combines an acidic dairyproduct production process and an infant formula product productionprocess in order to minimize the waste streams and at the same timeefficiently and cost-effectively produce both products with the need ofminimal supplementation. The inventors surprisingly found that thecomponents that are conventionally discarded as waste for one productform ideal components to be used in the production of the other product,such that waste streams are minimized and the need for supplementationof further components minimized. In other words, the casein that remainswhen producing an infant formula product from milk is ideally suited tobe used in the production of acidic dairy products, and, according to apreferred embodiment, the acid whey that remains when producing anacidic dairy product from casein according to the present invention isideally suited to be used in the production of an infant formulaproduct.

The inventive merit of the present invention resides not only in thefinding that left-over casein of infant formula product manufacture frommilk is ideally suited to produce acidic dairy products, but also in thefinding that the acid whey co-product of the latter process canefficiently be used in the manufacture of an infant formula product frommilk. Compared to the individual processes, the combined process formaking an infant formula product as well as an acidic dairy productaccording to the present invention reduces the need for addition ofexternal ingredients, especially in the production of infant formulaproducts and at the same time utilizes substantially all of thecomponents of the incoming defatted milk in valuable products. As such,the production of waste is largely avoided.

In a first aspect, the invention pertains to a process for producing aninfant formula product and an acidic dairy product from defatted animalmilk, comprising:

-   (a) processing the milk into a casein stream, a whey protein stream    and a lactose stream, by:    -   (i) subjecting the defatted animal milk to a filtration step        over a microfiltration membrane capable of retaining bacteria        and permeating milk proteins, to provide a debacterialized milk        as permeate;    -   (ii) subjecting the permeate originating from step (i) to a        filtration step over a microfiltration membrane capable of        retaining casein and permeating whey proteins, to provide a        casein stream as retentate and a permeate comprising whey        protein;    -   (iii) fractionating the permeate originating from step (ii) into        a whey protein stream and a lactose stream;-   (b) combining part of the casein stream, at least part of the whey    protein stream originating from step (a) and a lactose source to    obtain a recombined stream, wherein the lactose source comprises    acid whey;-   (c) using the recombined stream originating from step (b) in the    manufacture of the infant formula product;-   (d) using part of the casein stream originating from step (a) in the    manufacture of the acidic dairy product.

This process, including preferred embodiments thereof which are furtherdefined below, is also referred to as the process according to theinvention.

In a further aspect, the invention pertains to the infant formulaproduct obtainable by step (c) of the process according to theinvention. In one embodiment, this aspect of the invention pertains tothe infant formula product obtained by step (c) of the process accordingto the invention.

In a further aspect, the invention pertains to the acidic dairy productobtainable by step (d) of the process according to the invention. In oneembodiment, this aspect of the invention pertains to the acidic dairyproduct obtained by step (d) of the process according to the invention.

The lactose source employed in step (b) comprises or originates fromacid whey, preferably acid whey obtained as by-product during themanufacture of step (d). As such, acid whey is recycled from the acidicdairy product production to the infant formula product production,making particular efficient use of streams that conventionally are wastestreams. In a preferred embodiment, the lactose source is acid wheywhich is substantially devoid of minerals and proteins. The acid whey ispreferably subjected to demineralization and/or protein removal steps toyield said acid whey substantially devoid of minerals and proteins.

Herein, it is preferred that at least part of, preferably all of thelactose stream originating from step (a) is used as (part of) thelactose source in step (b) and/or is used in the manufacture of step(d). In one embodiment, the lactose source comprises at least part ofthe lactose stream originating from step (a) and acid whey, preferablyacid whey obtained as by-product during the manufacture of step (d).

Herein, it is preferred that all of the casein stream originating fromstep (a) is used in steps (b) and (d). Part of the casein streamoriginating from step (a) is used in the manufacture of step (d) andpart of the casein stream, preferably the remaining part, is subjectedto the combining of step (b) and included in the recombined stream.

Herein, it is preferred that all of the whey protein stream originatingfrom step (a) is used in step (b).

In the context of the present invention, whenever a certain stream orcomposition is mentioned to “originate from” a certain process step,such as from the recombined stream originating from step (b), saidstream or composition can be the composition which is directly obtainedby said process step. In addition, if such a directly obtained stream orcomposition undergoes one or more additional processing steps, such aspartial evaporation and/or supplementation of additional water or othercomponents, the stream or composition is also regarded to originate fromthat specific process step. Thus, if the recombined stream of step (b)would be partially evaporated prior to it is entered in the infantformula product manufacture of step (c), the incoming stream of step (c)is still regarded to be the recombined stream originating from step (b).

In one embodiment, the casein stream obtained in step (a) is useddirectly in step (b) and (d), without substantial alteration thereof. Inone embodiment, the whey protein stream obtained in step (a) is useddirectly in step (b), without substantial alteration thereof. In oneembodiment, the permeate obtained in step (i) is used directly in step(ii), without substantial alteration thereof. In one embodiment, thepermeate obtained in step (ii) is used directly in step (iii), withoutsubstantial alteration thereof.

In the context of the present invention, the term “stream” refers to aliquid composition, although the presence of some solid material is notexcluded, e.g. as in a suspension, as long as the composition can behandled by conventional dairy plants.

The process according to the invention produces two distinct products:an infant formula product and an acidic dairy product, both of which areobtained from defatted milk. In the context of the present invention,“infant formula product” refers to milk-based nutritional compositionssuitable for feeding infants, which typically are in the form of areconstitutable powder or a ready-to-feed liquid composition, or refersto infant formula bases, which are suitable for making infant formulaeand which comprise all or almost all essential ingredients in therequired amounts for infant nutrition. Preferably, the present processis for preparing infant formulae, follow-on formulae growing-up milks,or bases therefore. In the context of the present invention, the infantformula product is distinct from the acidic dairy product.

In the context of the present invention, “acidic dairy product” refersto fermented dairy products (e.g. yogurts) and acid cheeses, during theproduction of which acid whey is formed as by-product, such as cottagecheeses, strained yogurts or Greek-style yogurts. Acid dairy products,during the production of which acid whey is formed as by-product in themanufacture thereof, are particularly preferred as the acid whey isadvantageously used as lactose source in step (b) of the processaccording to the invention.

In a preferred embodiment, the acid dairy product is a strainedfermented dairy product. Processes for the production of strainedfermented dairy products are known in the art for example in WO2014/114970 or WO 2014/169171. Herein, “acid cheese” refers to acid typeof cheeses or “acid-coagulated cheeses”, such as cottage cheese orsimilar types of cheeses. As known in the art, acid cheeses are thosecheeses that give acid whey as by-product during their production. Inother words, acids are used to form coagulates in the production of acidcheeses. Such processes to produce acid cheeses are well-known in theart. In one embodiment, the acid cheese is selected from cottage cheeseand quark. Preferably, the acid dairy product as referred to herein is aproduct that includes in its production process a step wherein whey isseparated from the curd. Such separation may comprise centrifugation,filtration and/or straining.

The present process uses milk as starting material in step (a), andoptionally in step (d). Defatted animal milk is subjected to step (a)and may be used in combination with at least part of the casein streamin the manufacture of step (d). In the context of the invention,“defatted milk” refers to milk having a reduced fat content compared towhole milk. Typically the fat content of the defatted milk is in therange of 0-2 wt %, preferably 0-1 wt %, more preferably 0-0.2 wt %, mostpreferably 0-0.05 wt %, based on total weight of the defatted milk. Inone embodiment, the defatted milk is skim milk. The present processemploys animal milk, which refers to non-human milk, preferably cow'smilk. Most preferably, cow's skim milk is used. In one embodiment, theprocess comprises a step of defatting milk to obtain the defatted animalmilk, which is subsequently subjected to step (a). Herein, non-defattedanimal milk, or just animal milk or whole animal milk, is subjected tothe defatting step. The defatting step affords the defatted animal milk.

Although the process according to the invention may employ heat treatedmilk as incoming milk, it is preferred that the incoming defatted animalmilk is non-heat treated. In one embodiment, the process according tothe invention does not comprise any step of subjecting a liquid streamto pasteurization or sterilization, preferably not to any heattreatment, prior to being dried, typically by spray-drying, at the endof step (c). As such, the native state of the proteins are as much aspossible retained in the final products, which is beneficial forinfants.

Step (a)

In step (a), the defatted animal milk is processed or fractioned into acasein stream, a whey protein stream and a lactose stream. Herein, thecasein stream is a liquid composition comprising casein, which isenriched in casein compared to the casein content in the incomingdefatted animal milk, the whey protein stream is a liquid compositioncomprising whey protein, which is enriched in whey protein compared tothe whey protein content in the incoming defatted animal milk and thelactose stream is a liquid composition comprising lactose, which isenriched in lactose compared to the lactose content in the incomingdefatted animal milk. In the context of the present invention,“enriched” is defined that the content of the enriched component, basedon dry weight, is increased in one stream compared to another stream.Thus, the casein stream is enriched in casein, i.e. has a higher caseincontent, based on dry matter, compared to the incoming defatted animalmilk.

Step (a) employs membrane filtration techniques and involves acombination of microfiltration and ultrafiltration. Suitable membranefiltration processes are known in the art, e.g. as disclosed in WO2013/068653, WO 2013/137714 and WO 2015/041529.

Step (a) comprises:

-   (i) subjecting the defatted animal milk to a filtration step over a    microfiltration membrane capable of retaining bacteria and    permeating milk proteins, to provide a debacterialized milk as    permeate;-   (ii) subjecting the permeate originating from step (i) to a    filtration step over a microfiltration membrane capable of retaining    casein and permeating whey proteins, to provide a casein stream as    retentate and a permeate comprising whey protein; and-   (iii) fractionating the permeate originating from step (ii) into a    whey protein stream and a lactose stream.

In step (i), defatted animal milk is debacterialized by microfiltrationover a microfiltration membrane capable of retaining bacteria andpermeating milk proteins, to provide a debacterialized milk as permeate.Such bacterial filtration to remove bacteria from milk is known in theart.

In the microfiltration step (ii), defatted animal milk is fractionedinto two distinct streams, each enriched in a particular protein type; acasein enriched MF retentate (MFR) and a whey protein enriched MFpermeate (MFP) are produced. The MF step (ii) is performed over amembrane that enables fractionation of casein and whey proteins. Such amembrane typically has a porosity of 0.05-0.35 micrometer. Preferably, aceramic membrane or a spiral wound (organic) membrane is used.

According to a preferred embodiment, microfiltration of step (ii) isenhanced with diafiltration (DF). Diafiltration may be accomplished bydiluting the retentate of the MF at least once with an amount of water,or by diluting the incoming animal skim milk with an amount of water andsubjecting the diluted animal skim milk to MF. The DF water may be addedto the incoming animal skim milk or MFR at once, or the total amount ofDF water may be added in several fractions. After each addition of DFwater to the incoming animal skim milk or MFR, the diluted liquidcomposition is subjected to MF.

During ultrafiltration step (iii) most of the liquid and small solutesend up in the UF permeate (UFP), while the UF retentate (UFR) comprisessubstantially all whey protein, in a smaller volume. Small moleculeswhich permeate through the UF membrane are for example lactose,monovalent and polyvalent ions. The ultrafiltration of step (iii) can becarried out with any UF membrane known in the art, including ceramicmembranes, tubular and organic spiral wound membranes. Preferably the UFmembrane is an organic spiral wound membrane. The UF membrane has amolecular weight cut-off of that enables proteins, preferably wheyproteins, to remain in the retentate, and allow small solutes, forexample lactose, to permeate through the membrane. The UF step (iii)preferably is carried out with a membrane having a molecular weightcut-off of at most 25 kDa, more preferably at most 10 kDa, andpreferably of at least 2.5 kDa, more preferably at least 5 kDa. The UFstep (iii) is preferably carried out with a volume concentration factor(VCF) in the range of 20-200, preferably 50-150, which has been found toprovide the most optimal results in terms of the composition of the UFretentate.

In the context of the invention, the term “volume concentration factor”or “VCF” is the factor at which a liquid composition is concentratedupon filtration, i.e. the total volume of the incoming stream prior tofiltration divided by the total volume of the retentate afterfiltration, irrespective of the total solid content. Thus, when 5 L of aliquid composition is fractionated over an ultrafiltration membrane intoa permeate of 4 L and a retentate of 1 L, this UF process operates witha VCF of 5/1=5.

The protein fraction of the casein stream originating from step (a) inthe form of a microfiltration retentate typically comprises very littlewhey protein, preferably less than 15 wt %, more preferably less than 10wt %, based on the weight of the protein fraction of the casein stream,and is high in casein. Preferably the protein fraction comprises atleast 85 wt % casein, more preferably the protein fraction comprises atleast 90 wt % casein. The content of total solids in the casein streamtypically ranges from 5 to 30 wt %, preferably ranges from 7 to 30 wt %,most preferably from 17 to 24 wt %, based on total weight of the caseinstream. The casein stream is preferable a microfiltration retentate(MFR). The casein stream may also be referred to as a caseinconcentrate, casein isolate, micellar casein concentrate or micellarcasein isolate (MCI).

The whey protein stream is typically a liquid composition having a totalsolid content of 5-35 wt %, preferably of 10-30 wt %, most preferably of20-30 wt %, and typically comprises 25-90 wt %, preferably 60-85 wt %whey proteins based on total dry weight. The whey protein stream ispreferable an ultrafiltration retentate (UFR). The whey protein streammay also be referred to as an aqueous composition comprising wheyproteins.

Although the whey protein stream is enriched in whey protein compared tothe incoming defatted milk, it may still contain substantial amounts ofcasein, depending on the exact conditions at which the fractionationbetween casein and whey protein, typically by ultrafiltration, isperformed. In one embodiment, the whey protein stream comprises at most40 wt %, preferably 5-20 wt % casein, based on total weight of theprotein. Such variations in the fractionation conditions and theaccompanying changes in the whey protein stream are known in the art.Depending on the amount of casein present in the whey protein stream,the amount of casein used in combining step (b) can be adapted such thatthe infant formula product has a whey protein:casein ratio that fallswithin the preferred ratio of 90:10 to 40:60.

The lactose stream is typically a liquid composition having a totalsolid content of 3-30 wt %, preferably of 5-22 wt %. The lactose contentin the lactose stream originating from step (a) is typically at least 75wt %, preferably at least 90 wt % or even at least 95 wt %, based ontotal dry weight.

Demineralization

The process according to the invention preferably comprises ademineralization step, wherein the lactose source, or one or morecomponents thereof, is/are demineralized prior to being subjected tostep (b). Demineralization is thus typically performed on at least partof the lactose stream originating from step (a) and/or on the acid wheyoriginating from step (d), preferably at least the acid whey originatingfrom step (d) is subjected to demineralization prior to being subjectedto step (b). Demineralization is particularly preferred for themanufacture of infant formula products, for which it is typicallyrequired to lower the mineral content as compared to the incoming milk.

Thus, in one embodiment, the acid whey, preferably the acid wheyoriginating from step (d), is subjected to demineralization prior tobeing used as (part of) the lactose source in step (b). Likewise, in oneembodiment, at least part of the lactose stream originating from step(a), preferably the UFP originating from step (iii), is subjected todemineralization prior to being used as (part of) the lactose source instep (b).

In case the lactose stream originating from step (a) is not subjected tostep (b) but for example to step (d), demineralization of the lactosestream is typically not required, as the desired mineral content ofacidic dairy products typically more or less corresponds to the mineralcontent of the incoming milk. In case part of the lactose streamoriginating from step (a) is subjected to step (b) and part is subjectedto step (d), it is preferred that only that part that is subjected tostep (b) is first subjected to demineralization.

In a preferred embodiment, acid whey that originates from step (d) issubjected to step (b) as (part of) the lactose source, and subsequentlyto the manufacture of the infant formula product of step (c). It is thuspreferred that the acid whey is demineralized prior to step (b). Hence,in a preferred embodiment, the acid whey originating from step (d) iscombined with the part of the lactose stream originating from step (a),if any, and the combined lactose source is subjected to demineralizationprior to subjecting them to step (b).

Demineralization of the lactose source may be performed by any techniqueknown in the art, such as electrodialysis, ion exchange, saltprecipitation, lactose crystallization, membrane filtration techniquessuch as nanofiltration, optionally enhanced with diafiltration, orcombinations thereof. In a preferred embodiment, demineralizationcomprises at least one of salt precipitation, electrodialysis, lactosecrystallization and ion exchange, optionally in combination withnanofiltration, more preferably demineralization comprisesnanofiltration in combination with at least one of salt precipitation,electrodialysis, lactose crystallization and ion exchange. In preferredembodiment, demineralization comprises at least electrodialysis and/orsalt precipitation. In one preferred embodiment, demineralizationcomprises at least nanofiltration in combination with electrodialysisand/or salt precipitation. The inventors found that when onlynanofiltration is used for demineralization, especially fordemineralization of an ultrafiltration permeate as lactose source in thepreparation of infant formula products, the content of divalent ions,such as calcium and phosphate, is typically insufficiently reduced toobtain a final infant formula product within legal requirement.

Demineralization is preferably performed such that at least 20 wt %, orpreferably 50 wt %, more preferably at least 70 wt % or at least 80 wt%, most preferably at least 90 wt % of the polyvalent ions and/or suchthat at least 20 wt % of the monovalent ions are removed, morepreferably at least 35 wt % or at least 50 wt %, most preferably atleast 60 wt % of the monovalent ions, present in the lactose stream,e.g.t the UFP originating from step (iii), are removed.

Step (b)

In step (b), part of the casein stream, at least part of the wheyprotein stream originating from step (a) and a lactose source arecombined to obtain a recombined stream. This recombined stream is usedto manufacture the infant formula product in step (c). The combining ofstep (b) affords a composition having a protein fraction comprising bothcasein and whey protein in a certain weight ratio.

The combining is preferably done such that the whey protein to caseinweight ratio in the recombined stream is in the range of 90:10 to 40:60,more preferably in the range of 80:20 to 50:50, even more preferably inthe range of 75:25 to 50:50, most preferably in the range of 70:30 to55:45. In one embodiment, the whey protein to casein weight ratio in therecombined stream is about 60:40. The exact ratio is typicallydetermined by the type of infant formula product that is being produced,and can be adjusted as known in the art. In addition, much attention inthe art is given to the amino acid profile of infant formula products.The process according to the invention provides optimal flexibility intargeting a specific desired amino acid profile, e.g. by adjusting theratio in which the whey protein and casein streams are combined or invarying the specific process conditions of the microfiltration of step(a). As such, optimal amino acid profiles resembling those found inhuman milk are obtainable with the process according to the invention.

As infant formula products typically require the presence of less caseinand more whey protein as present in the defatted animal milk which issubjected to step (a), not all of the casein stream is needed in orderto recombine with the whey protein stream. The present invention putsthis remaining casein, which is presently mostly discarded, to good use,in the manufacture of step (d).

Typically, all of the casein stream originating from step (a) is used instep (b) and step (d), such that no further casein is remaining orleft-over. In other words, the casein stream originating from step (a)is preferably divided over steps (b) and (d). It is thus preferred thatpart of the casein stream originating from step (a) is used in themanufacture of step (d) and part of the casein stream, preferably theremaining part, is subjected to the combining of step (b) and includedin the recombined stream.

In one embodiment, 10-50 wt %, preferably 12-25 wt %, based on totalweight of the casein, of the casein stream originating from step (a) issubjected to step (b). Most preferably, about 16 wt %, based on totalweight of the casein, of the casein stream originating from step (a) issubjected to step (b). Most preferably, the remainder is subjected tostep (d). The amount of the casein stream originating from step (a) thatis subjected to step (b) is advantageously governed by the desired wheyprotein to casein weight ratio in the recombined stream.

Preferably, all of the whey protein stream originating from step (a) issubjected to the combining of step (b). Likewise, it is preferred thatall of the acid whey originating from step (d) is subjected to step (b).Making such use of the whey protein stream originating from step (a) andthe acid whey originating from step (d) minimizes the amount of wastethat is discarded by the process and optimally utilizes all componentsof the incoming milk.

The presence of lactose is typically required for both the infantformula product manufacture of step (c) as well as the acidic dairyproduct manufacture of step (d), especially in case the diary product isa yogurt. Hence, in the process according to the invention, it ispreferred that at least part of, preferably all of, the lactose streamoriginating from step (a) is subjected to step (b) and/or to step (d).In a preferred embodiment, the lactose stream originating from step (a)is divided over steps (b) and (d). Thus, in one embodiment, at leastpart of the lactose stream originating from step (a) is subjected tostep (b). In this embodiment, step (b) involves combining part of thecasein stream and at least part of the whey protein and the lactosestreams originating from step (a) and at least part of the acid wheyoriginating from step (d), into a recombined stream. In one embodiment,0-50 wt %, preferably 5-25 wt %, based on total weight of the lactose,of the lactose stream originating from step (a) is subjected to step (b)as (part of) the lactose source. Most preferably, the remainder issubjected to step (d). The amount of the lactose stream originating fromstep (a) that is subjected to step (b) as (part of) the lactose sourceis advantageously governed by the amount of lactose required for step(d). In case the amount of lactose in the lactose stream originatingfrom step (aiii) that is subjected to step (b) would be insufficient forinfant formula product manufacture, additional lactose can be used thatis present in the acid whey originating from step (d). Hence, not allthe lactose of the lactose stream may be needed in order to afford thedesired lactose content in the recombined stream, such that remaininglactose may beneficially be used in step (d) as additive during theproduction of the acidic dairy product, as such further reducing theamount of waste.

In one embodiment, part of the casein stream is combined with all of thewhey protein stream, part of the lactose stream and all of the acidwhey. In one embodiment, part of the casein stream is combined with allof the whey protein stream, all of the lactose stream and all of theacid whey. In one embodiment, part of the casein stream is combined withall of the whey protein stream, nothing of the lactose stream and all ofthe acid whey.

In one embodiment, part of the MFR originating from step (ii) iscombined with at least part of the UFR originating from step (iii), atleast part of the UFP originating from step (iii), and the acid wheyoriginating from step (d).

In step (b), two or more streams are recombined into one stream. Thisrecombining may occur at once (streams are combined simultaneously) orstep-wise (streams are combined consecutively). In one embodiment, theacid whey originating from step (d) is combined prior todemineralisation with the lactose stream originating from step (iii),such that they can be both demineralized prior to being combined withthe casein and whey protein streams. Combining can be performed as wetmixing or as dry mixing or even as a combination of both. Preferably,the combining occurs as wet mixing, wherein liquid compositions aremixed in the appropriate amounts.

Step (c)

In step (c), the recombined stream originating from step (b) is used tomanufacture the infant formula product. Such manufacturing is known inthe art and typically involves one or more of drying, concentrating,supplementing with vitamins, minerals, lipids and/or dietary fibres,heat treatment, homogenisation, packaging. In a preferred embodiment,step (c) does not involve heat treatment, and involves one or more ofdrying, concentrating, supplementing with vitamins, minerals, lipidsand/or dietary fibres and packaging. Preferably, step (c) involves atleast a drying step, most preferably it involves all of the abovementioned steps.

Although one or more of the separate streams may be dried prior to beingcombined in step (b), it is preferred that the recombined streamoriginating from step (b) is dried, preferably spray-dried. As such,only one drying step is needed in the manufacture of the infant formulaproduct. Moreover, drying typically reduces the content of nativeprotein, and performing multiple drying steps thus leads to a reducedcontent of native protein in the final infant formula product. In apreferred embodiment, the process according to the invention comprisesonly a single drying step, wherein in step (c) the recombined stream isdried, preferably by spray-drying. Due to the inherent limited heat-loadexerted on the liquid nutritional composition by spray-drying,significant amounts of protein remain native during this step, such thatthe content of native protein in the final infant formula product is ashigh as possible.

In one embodiment, the recombined stream is concentrated, preferablyprior to being dried. Such concentration may be accomplished by anymeans known in the art, such as by reverse osmosis (RO), nanofiltration(NF) and/or evaporation.

Heat treatment is known in the art and may e.g. be performed bypasteurization, such as HTST, ESL or UHT, or sterilization, for exampledry heat or moist heat sterilization. As debacterisation occurs duringstep (i), it is preferred that no further heat treatment is performed inthe manufacture of step (c).

Depending on the desired type of infant formula product, supplementationof certain components, such as vitamins, minerals, lipids and/or dietaryfibres, may be desired. Such supplementation can be performed eitherprior to, during or after combining step (b) and/or optionally prior toor after a drying step. The skilled person is aware of the requirementsof particular types of infant formula products, e.g. from EU directive91/321/EEC or EU directive 2006/141/EC or US Food and DrugAdministration 21 CFR Ch 1 part 107, and is able to adjust thecomposition of the recombined stream in order to meet thoserequirements.

In one aspect, the present invention concerns the infant formula productobtainable by the process according to the invention, i.e. obtainable bystep (c). The inventors have found that the digestibility of the proteinfraction in the infant formula product according to the invention, i.e.as obtainable by the process according to the invention, is improvedcompared to protein fractions of known infant formula products. Herein,an improved digestibility refers to a digestibility closer to that ofhuman milk. Digestibility typically refers to the rate of digestion,preferably the rate of protein digestion. Also, the whey proteinobtainable by the method of the present invention constitutes aneconomically attractive protein source to be included in infantformulae.

In one aspect, the present invention concerns the whey protein aspresent in the whey protein stream obtainable by the process accordingto the invention, i.e. obtainable by step (a) (iii), which is comprisedby an infant formula product obtainable by step c). Said protein productexhibits improved digestibility, also in dried form. Said whey proteinis preferably present with casein in a ratio of whey protein:casein inthe range of 90:10 to 40:60, more preferably in the range of 80:20 to50:50, even more preferably in the range of 75:25 to 50:50, mostpreferably in the range of 70:30 to 55:45. The whey protein obtainableby the present invention exhibits digestion kinetics closer to humanmilk than currently commercialized infant formula.

The skilled person is capable of determining the extent ofdigestibility, e.g. from Van de Braak et al. (Clin. Nutr. 2013, 32,765-771). A preferred method for determining digestibility is accordingto the following Digestibility Test:

Digestibility Test

Gastric and intestinal conditions are simulated successively withinconsecutive bioreactors in a parallel bioreactor system. Within eachreactor, the conditions are dynamic in the sense that the pH follows apre-set curve and fresh artificial digestive juices are continuousadded. The biochemical gastric and intestinal conditions, i.e. enzymeactivity, bile concentrations and pH, are adjusted to mimic those ofinfants ingesting a dose of infant formula of 200 ml. Gastric digestionis mimicked by addition of pepsin/lipase solution (10 ml shot+0.5ml/min), containing 37.5 mg Lipase (DF Amano 15) and 15 mg Pepsin (SigmaP7012) per 300 ml, while gradually decreasing pH to 4.3 by adding HClover 2 hours. Intestinal digestion was mimicked at neutral pH (7.2) uponaddition of sodium hydroxide/sodium carbonate and pancreatin/bileextract (45 ml shot+1 ml/min) containing 7.5 g pancreatin (4×USP,Pfizer) and 2.5 g bile extract (porcine powder Sigma B8631) per 500 ml,in 2 hours. At regular intervals, sampling is performed to followprotein digestion in time. Samples are subjected to chemical analysis,including: disappearance of substrate by SDS-page and SEC-HPLC,generation ofprimary amino groups by OPA, small peptide formation bySEC-HPLC, and formation of free amino acids by UPLC. Using thisprotocol, the rate of digestion of one component, such as a proteinsource or a food product containing the protein source, can readily becompared to the rate of digestion of another protein source or a foodproduct containing the protein source.

In a further preferred embodiment, the present invention relates to aninfant formula obtainable by step c) containing the milk proteinsobtainable by the method of the present invention, i.e. obtainable bystep a). Said milk proteins preferably include whey protein and casein,preferably present in a ratio in the range of 90:10 to 40:60, morepreferably in the range of 80:20 to 50:50, even more preferably in therange of 75:25 to 50:50, most preferably in the range of 70:30 to 55:45.The whey and casein proteins obtainable by the present invention exhibitdigestion kinetics closer to human milk than currently commercializedinfant formula. Preferably, the casein and whey proteins obtainable bythe present invention exhibit digestion kinetics wherein after two hoursof digestion, preferably gastric digestion, more than 70% of totalcasein and whey protein as initially administered is still intact. Morepreferably said digestion kinetics are such that after two hours ofdigestion more than 80% of the initially administered casein and wheyprotein is still intact. Preferably said digestion kinetics areaccording to the digestion test as mentioned in Example 2. Preferablysaid digestion kinetics are according to the digestion test as mentionedin Example 2.

Preferably, the whey proteins obtainable by the present inventionexhibit digestion kinetics wherein after two hours of digestion,preferably gastric digestion, more than 70% of total whey protein asinitially administered is still intact. More preferably said digestionkinetics are such that after two hours of digestion more than 80% oreven 90% of the initially administered whey protein is still intact.Preferably said digestion kinetics are according to the digestion testas mentioned in Example 2.

In one aspect, the invention concerns a method or use for improvingdigestibility of a protein fraction comprised in an infant formulaproduct, comprising preparing the infant formula product with theprocess according to the present invention. In one aspect, the inventionconcerns a method or use for feeding a human infant, preferably a humaninfant of 0-6 months of age, comprising administrating the infantformula product according to the invention to said infant.

In one embodiment, the invention concerns the use of the proteinfraction obtainable by step (a) of the process according to theinvention, in particular the whey protein stream obtainable by step(iii), for improving the digestibility of an infant formula product.Herein, improved digestibility is as defined herein and typically refersto improved digestion kinetics, i.e. digestion kinetics closer as thedigestion kinetics observed for human milk. According to the presentaspect, the whey protein obtainable by step (a), (iii) of the processaccording to the invention, is used as part of or as the completeprotein fraction in the infant formula product. Preferably, the proteinfraction is obtainable by step (a) and part of step (b), wherein thecasein stream is combined with the whey protein stream. This inventorsfound that the whey protein stream according to the invention, inparticular when combined with the casein stream according to theinvention, exhibited improved digestibility.

The use according to the present aspect can also be worded as an infantformula product comprising the protein fraction as defined herein foruse in improving digestibility, or as a method for improvingdigestibility, comprising administering to a subject in need thereof,typically a human infant, an infant formula product comprising theprotein fraction as defined herein, or as use of the protein fraction asdefined herein for the manufacture of an infant formula product forimproving digestibility. The use, method or infant formula product foruse according to the present aspect can be medical or non-medical.

Step (d)

In step (d), part of the casein stream is further processed to obtain anacidic dairy product. In a preferred embodiment, acid whey is obtainedas by-product. The acidic dairy product is manufactured from at leastpart of the casein stream originating from step (a) and optionally fromdefatted animal milk. Preferably, the defatted animal milk is the sameanimal milk as subjected to step (a), and preferably has undergone thesame pretreatment steps, if any.

Acid whey, also referred to as sour whey, is a co-product ofconventional process for the production of acidic dairy products, and isnormally discarded as waste. Acid whey comprises valuable compounds suchas lactose. In view of the rapidly increasing demand for acidic dairyproducts, in particular yogurts, the increasing acid whey waste streamis becoming a serious problem for the dairy industry, which is elegantlysolved by the present invention. Preferably, all or part of the lactosestream originating from step (a) is used in the manufacturing of step(d). Any means known in the art to manufacture acidic dairy products canbe used as step (d), such as a process for the manufacture of yogurts ora process for the manufacture of acid cheeses. Step (d) typicallyinvolves a process for the production of an acid cheese or yogurt,preferably of a strained yogurt product from casein as known in the art.

Step (d) typically comprises a combining step, wherein the casein streamoriginating from step (a) is combined with one or more of a whey proteinsource (e.g. milk, whey protein concentrate (WPC), whey protein isolate(WPI)), cream, minerals and lactose. Herein, milk is preferably defattedanimal milk, more preferably the same defatted animal milk that issubjected to step (a). Herein, the lactose may originate from step (a),from a demineralization step, preferably the demineralization stepaccording to the present invention, or from an external source, mostpreferably the lactose at least partly originated from step (a).Minerals are preferably added, most preferably in the form of thelactose stream originating from step (a) that has not undergonedemineralisation. Most preferably, the casein stream originating fromstep (a) is combined with at least a whey protein source, preferablydefatted animal milk. Preferably, this combining is the first step inthe manufacture of step (d). In other words, a mixture comprising atleast part of the casein stream originating from step (a) and a wheyprotein source, preferably defatted animal milk, is manufactured into anacidic dairy product. Thus, in one embodiment, step (d) uses at leastpart of the casein stream originating from step (a) and defatted animalmilk in the manufacture of the acidic dairy product. The combining ispreferably performed such that the weight ratio of protein from thecasein stream to protein from the whey protein source is in the range of0.1-9.0, most preferably in the range 0.5-2.0.

The presence of a whey protein source ensures that whey protein andlactose are present during manufacture of the acidic dairy product. Afurther lactose source, such as (part of) the lactose stream originatingfrom step (a), may also be used in the manufacture of step (d), and ispreferably combined with the casein stream originating from step (a) andthe defatted animal milk during step (d).

Step (d) preferably comprises a centrifugation step wherein solids, thateventually form the acidic dairy product, are separated from a liquidstream that is obtained as acid whey. In a preferred embodiment, theacid whey used in the lactose source is obtained as a liquid stream froma centrifugation step during the manufacture of step (d). The combiningof casein, whey protein and lactose to manufacture acidic dairy productsis known in the art and may be accomplished as deemed fit by the skilledperson.

Typically, all of the casein stream originating from step (a) is used ineither step (b) or in step (d), such that no further casein isremaining. In one embodiment, 50-90 wt %, preferably 75-88 wt %, basedon total weight of the casein, of the casein stream originating fromstep (a) is subjected to step (d). Most preferably, about 84 wt %, basedon total weight of the casein, of the casein stream originating fromstep (a) is subjected to step (d). Most preferably, the remainder issubjected to step (b).

Likewise, it is preferred that all of the lactose stream originatingfrom step (a) is used in either step (b) or in step (d), such that nofurther lactose is remaining. In one embodiment, 50-100 wt %, preferably75-95 wt %, based on total weight of the lactose, of the lactose streamoriginating from step (a) is subjected to step (d). Most preferably, theremainder is subjected to step (b).

In a preferred embodiment, defatted animal milk is the sole proteinsource for both products that are obtained by the process according tothe invention. Preferably, all protein of the acidic dairy product thatis obtained in step (d) originates from the casein stream and optionallyfrom the same animal skim milk that is subjected to step (a). As such,the animal skim milk is the sole source of protein for the acidic dairyproduct. Any other additive or component, known in the art to besuitable for the preparation of acidic dairy products, may be added tothe casein stream, the animal milk or the combination thereof. Suitableadditives include milk fat, stabilizers, sweeteners, flavours, and thelike. The use of milk that has been enriched with such additives toproduce acidic dairy products is known in the art.

In a preferred embodiment, the manufacture of the acidic dairy productof step (d) affords acid whey as by-product, which is conventionallydiscarded as waste. Acid whey is known in the art and refers to a wheystream that is obtained in the production of acidic dairy products suchas yogurts and acid cheeses. Acid whey is typically a liquidcomposition, characterized by a pH of at most 5.5 or even at most 5.1.Acid whey typically contains, based on total dry weight 50-90 wt %,preferably 60-75 wt % lactose and 0-20 wt %, preferably 10-15 wt % wheyprotein. Acid whey further typically comprises minerals, includingcalcium, potassium, magnesium, sodium, chloride and phosphate. The totalamount of ash in acid whey is typically in the range of 8-20 wt %,preferably 10-15 wt %, based on total dry weight.

The acid whey that originates from step (d) is preferably subjected tothe combining of step (b) to be used as (part of) the lactose source inthe production of the infant formula product. The ash content of acidwhey can be undesirably high, and is thus preferably reduced bydemineralization prior to being combined in step (b) with the wheyprotein stream and possibly part of the casein stream originating fromstep (a). In one embodiment, the acid whey originating from step (d) iscombined with the lactose stream prior to demineralization of thecombined lactose and acid whey streams. In case the lactose stream wouldnot require demineralization, the acid whey may be subjected todemineralization without prior combination with the lactose stream. Suchdemineralization may be accomplished by any means known in the art.

FIGURES

FIG. 1 depicts a preferred embodiment of the process according to theinvention. Dotted arrows indicated preferred embodiments.MF1=microfiltration step (i); MF2=microfiltration step (ii);UF=ultrafiltration; Demin=demineralisation; AD=acidic dairy product;IF=infant formula product; L=lactose source. The different streams arerepresented by numbers 1-9: 1=defatted animal milk; 2=debacterializedmilk; 3=microfiltration retentate; 4=microfiltration permeate;5=ultrafiltration retentate; 6=ultrafiltration permeate; 7=recombinedstream; 8=acid whey; 9=demineralized lactose.

FIG. 2 depicts the results of Example 2, wherein the protein fraction ofan infant formula according to the invention (solid line) was found tobe more slowly digested then a conventional formula (dotted line).Int=intensity of the combined protein bands in an SDS-PAGE gel, in %based on the intensity at t=0 min.

EXAMPLES Example 1

Defatted Milk Processing into a Native Whey Protein Stream

Whole raw milk (purchased from Dairygold) was processed into a WPCfraction according to the following process. Milk and subsequentfractions were stored at 4° C. throughout production. Whole milk wasskimmed using typical GEA Westfalia Separator @55° C. and cooled to 4°C. Skim milk was subjected to microfiltration to separate casein fromboth whey and lactose. Microfiltration membrane used was a 0.08 μMSynder membrane FR (PVDF 800 kDa) spiral wound membrane. However, anymicrofiltration membrane could be used provided casein was retainedwhile whey/lactose/soluble minerals permeate efficiently.Microfiltration retentate was kept as the casein fraction.Microfiltration permeate contained whey and lactose.

Operating temperature was 10° C. and concentration factor (CF) was 3. CFfactor achieved related to required final concentration of caseinprotein in microfiltration retentate. Microfiltration permeate was thensubjected to ultrafiltration to separate whey protein from lactose atoperating temperature of 10° C. with VCF of 90. CF factor achievedrelated to required final concentration of whey protein inultrafiltration retentate. In this trial a WPC70 was produced.

The ultrafiltration membrane used was a 10 kDa Synder membrane ST (PES10 kDa) spiral wound membrane. However, any ultrafiltration membranecould be used provided whey proteins were retained and lactose andminerals permeate efficiently. Diafiltration medium was added to improveseparation efficiency of membranes (200% of original starting skim milkvolume). Concentrated liquid WPC70 (DM 11%) was stored at 4° C.

Liquid WPC 70 was heated to 30° C. and spray dried at 11% DM. Spraydryer used was a single stage pilot scale dryer operated with an inlettemperature of 185° C. and outlet temperature of 90° C. Dried WPC70 wasthen recombined with a casein source, lactose and minerals to matchthose of infant formulae compositions.

A commercially available infant formula (Frisolac Gold, casein at 4.2g/100 g dry product or 0.55 g/100 ml ready-to-feed, whey protein at 6.4g/100 g dry product or 0.83 g/100 ml ready-to-feed) was purchased andused in comparison to a composition comprising the whey proteinsobtained according to above described process of Example 1.

Example 2

Digestibility Test

This protocol describes the simulation of digestion processes by use ofthe Multi-fermenter fed-batch from DasGip. The conditions used arespecifically designed to simulate the digestion of a dose of infantformula of 200 ml by an infant of 6-12 months of age. The volumesdescribed in this protocol are all scaled down by a factor 0.175 topermit usage of 0.1 litre reactors with overhead magnetic agitation witha starting volume of 35 ml Infant Formula (IF).

Preparation of Solutions

Fresh stock solutions as used during the digestibility test are preparedbefore the test is started. 20× concentrated gastric electrolytesolution with a density of 1.05438 g/ml is prepared in demi-water bydissolving 62 g NaCl, 22 g KCl, 3 g CaCl₂.2H₂O by stirring intodemi-water until a volume of 1000 ml is reached. 1 L saliva electrolyte(1×) is prepared in demi-water by dissolving 6.2 g NaCl, 2.2 g KCl, 0.3g CaCl₂.2H₂O and 1.2 g NaHCO₃ and adjusting the pH to 6.3 withconcentrated HCl. Sodium acetate buffer is used with a pH of 5.0 at 0.93M/1.25× concentrated Small Intestine Electrolyte Solution (SIES) with adensity of 1.09275 g/ml is prepared by adding 125 g NaCl, 15 g KCl and7.5 g CaCl₂.2H₂O and adjusting the pH to 7 with concentrated NaOH.Intestinal protease inhibitor solution contains trypsin and chymotrypsininhibitor (Glycine max, SIGMA, T9777) dissolved in milliQ water at 0.58mg/ml. 2 ml is used per intestinal sample. Hydrochloric acid (Merck,Substrate A) is used at 0.25M. NaHCO₃/NaOH solution (Substrate B) isprepared by dissolving 84 g NaHCO₃ and 40 g NaOH.

Fresh Working Solutions are Prepared as Follows.

50 ml Saliva is prepared by adding 30 mg α-amylase (Sigma A-6211) to 50ml saliva electrolyte of which 5.8 ml is added into each reactor beforeinoculation. 300 ml gastric juice is prepared by adding 15 ml gastricelectrolyte concentrated stock and 3 ml 1M sodium acetate buffer pH=5.0to 282 ml demi-water of which 12.3 ml is needed per reactor. Solution iscooled on ice and enzymes are added when temperature reaches atemperature of below 8° C. Next, add 37.5 mg Lipase DF Amano 15 and 15mg Pepsin (Sigma P7012-109) and mix for 10 minutes. Store on ice. 500 mlIntestinal Juice is prepared by adding 2.5 g bile extract porcine powder(Sigma) to 250 ml while gradually dissolving in 250 ml cold demi-waterand dissolving in 150 ml of cold demi-water of 7.5 g pancreatin (Pfizer)and combining 115 ml cold demi-water with 250 ml Bile solution and 125ml Pancreatin solution with 10 ml SIES concentrated stock to a total of500 ml. During the experiment, the solution is kept on ice and mixedcontinuously. 31.5 ml is used per reactor.

Apparatus and Testing of Samples

Test products of Example 1 are placed into the Multifermentor fed-batch(DasGip) reactors and the apparatus is operated according to themanufacturer's instructions. Magnetic stirring is used at 200 rpm to mixacid and enzymes during digestion. Briefly, 38 ml test sample is addedto the reactors and at distinct sample time points (from t=0 minutes tot=130 minutes) a predetermined amount of sample (3 ml at t=0 and 2 ml atfollowing time points) is extracted, snap frozen and stored for furtheranalysis by SDS PAGE and quantification of the amount of signal fromdistinct protein bands.

Solution Injection Scheme

SIM Lapsed sample Sample time time pH point vol. Remarks 00:00 0 6.8  03 ml 00:05 5 6.8 — — Start addition of gastric juice 00:15 15  10′ 2 ml00:25 25 6.5 — — 00:35 35  30′ 2 ml 00:45 45 6.2 — — 01:05 65 5.8  60′ 2ml 01:35 95 5.0  90′ 2 ml 02:05 125 4.3 120′ 2 ml Stop addition ofgastric juice 02:10 130 5.4 — — 02:15 135 6.5 — — Start addition ofintestinal juice 02:17 137 122′ 2 ml 02:21 141 6.7 126′ 2 ml 02:25 145130′ 2 ml

Gastric juice is injected with a flow of 40.25 ml/h for 3 minutes fromSIM time point 00:05:01 to 00:08:01, followed by injection at 5.25 ml/huntil 2:04:59. Intestinal juice is injected with a flow of 80.5 ml/h for9 minutes from SIM time point 2:15:00 to 2:23:59, followed by injectionat 10.5 ml/h for the remainder of the test. First column indicates theSIM time as used by the SIM machine. Second column indicates lapsed timeduring the experiment. Time points in the fourth column (sample point)correspond to the time indicated in FIG. 2 and takes adaptation of thesystem to injection of solutions into account. The gastric phase runsfrom sample points t=0 up to t=120. The intestinal phase runs fromsample point t=122 up to t=130.

Following such an established protocol allows mimicking of milk proteindigestion kinetics contained in infant formulae in a representativemanner.

It was observed that the whey protein fraction, as obtained according tothe process of Example 1, displayed a slower protein digestion kineticthan the commercially available infant formula as tested. Fast digestionkinetics, similar to the commercially available infant formula, wereobserved when the whey protein fraction obtained via the process ofexample 1 was subjected to a heat treatment, such as a treatment whereinthe WPC70 was subjected for 10 minutes to 80° C. It was also observedthat the presence of fat in the infant formula did not interfere withthe slowed, improved whey protein digestion kinetics since similarresults were obtained with or without the presence of fat in the testedcomposition.

Since it is known that slower protein digestion is beneficial forinfants and occurring in human milk compared to commercially availableinfant formula, it is desirable to produce infant formula of which atleast the protein fraction, in particular the whey proteins containedtherein, show a digestion kinetic that more closely resembles human milkdigestion.

The invention claimed is:
 1. A process for producing an infant formulaproduct and an acidic dairy product from defatted animal milk,comprising: (a) processing the defatted animal milk into a caseinstream, a whey protein stream and a lactose stream, by: (i) subjectingthe defatted animal milk to a filtration step over a microfiltrationmembrane capable of retaining bacteria and permeating milk proteins, toprovide a debacterialized milk as permeate; (ii) subjecting the permeateoriginating from step (i) to a filtration step over a microfiltrationmembrane capable of retaining casein and permeating whey proteins, toprovide a casein stream as retentate and a permeate comprising wheyprotein; (iii) fractionating the permeate originating from step (ii)into a whey protein stream and a lactose stream; (b) combining part ofthe casein stream, at least part of the whey protein stream originatingfrom step (a) and a lactose source to obtain a recombined stream,wherein the lactose source comprises acid whey; (c) using the recombinedstream originating from step (b) in the manufacture of the infantformula product; (d) using part of the casein stream originating fromstep (a) in the manufacture of the acidic dairy product.
 2. The processaccording to claim 1, wherein the acid whey is obtained as a liquidstream from a separation step during the manufacture of an acidic dairyproduct.
 3. The process according to claim 1, wherein the acid whey issubjected to demineralization prior to being used as lactose source instep (b).
 4. The process according to claim 3, wherein thedemineralization comprises at least one of salt precipitation,electrodialysis, lactose crystallization and ion exchange.
 5. Theprocess according to claim 3, wherein the acid whey and at least part ofthe lactose stream originating from step (a) are combined andsubsequently subjected to the demineralization prior to being used aslactose source in step (b).
 6. The process according to claim 1, whereinthe combining of step (b) is done such that the whey protein to caseinweight ratio in the recombined stream is in the range of 90:10 to 40:60.7. The process according to claim 1, wherein step (iii) is performed byultrafiltration.
 8. The process according to claim 7, wherein theultrafiltration step operates at a volume concentration factor in therange of 20-200.
 9. The process according to claim 1, wherein themanufacturing of step (c) includes at least one of drying,concentrating, supplementing with vitamins, minerals, lipids and/ordietary fibres and packaging.
 10. The process according to claim 1,wherein the defatted animal milk is the sole protein source for theinfant formula product.
 11. The process according to claim 10, whereinthe defatted animal milk is the sole protein source for the both infantformula product and the acidic dairy product.
 12. The process accordingto claim 4, wherein the demineralization is in combination withnanofiltration.